The present invention relates to apparatus and methods for thermal treatment of the endometrium. More particularly, the present invention relates to an apparatus for applying ablation energies to the entire surface of the endometrium in a controlled manner. A preferred embodiment of the invention comprises an optionally transparent inflatable coolable balloon operable to cool the endometrium, cryoprobes operable to be advanced into and to cool the uterine cornuae, an applicator operable to deliver balloon and cryoprobes to and from the uterine cavity, and optional channels for a hysteroscope and a light source, enabling observation of all aspects of the ablation process. The apparatus and method are particularly useful for treatment of dysfunctional uterine bleeding.
Dysfunctional uterine bleeding (hereafter “DUB”) is menstrual bleeding which deviates from normal menstrual patterns, either in the frequency of menstruation or in the duration or amount of bleeding, in the absence of pregnancy, infection, tumor or other organic lesion. DUB is reported to affect 20% of women worldwide and is even higher during adolescence and the decade preceding menopause. The most frequent cause of dysfunctional uterine bleeding is anovulation. The proportion of cases of dysfunctional uterine bleeding in the presence of ovulation is apparently very low. In the West, dysfunctional uterine bleeding is reported to be the leading cause of iron deficiency anemia.
The objective of treatment is twofold: to eliminate excessive bleeding and to improve the patient's quality of life.
The first-line treatment of dysfunctional uterine bleeding is usually medical. Hormone therapy often the basis of treatment, since in most cases the underlying cause of dysfunctional uterine bleeding is anovulation. In the absence of a causal disease in a woman who ovulates and who has dysfunctional uterine bleeding, nonsteroidal antiinflammatories (NSAIDs) and antifibrinolytics are used. Danazol and gonadoliberin agonists are used in the treatment of menstrual bleeding refractory to the other forms of medical therapy.
However, medical treatment is seldom a lasting solution to dysfunctional uterine bleeding and is not without adverse effects.
When drug therapy fails, surgical intervention is generally the next option.
Curettage stabilizes bleeding in some women, but its effects are almost never long-lasting. This procedure is therefore not recommended in the treatment of dysfunctional uterine bleeding.
Uterine artery embolization has occasionally been used for patients presenting barriers to major invasive surgery, but the long-term efficacy and safety of this surgical treatment modality have not yet been demonstrated for dysfunctional uterine bleeding.
Hysterectomy has, for many years, been the most widely used treatment for DUB. It can be performed abdominally, vaginally or laparoscopically. The vaginal and laparoscopic approaches are reported to cause fewer complications and to result in a shorter hospital stay and convalescence than the abdominal approach. However, hysterectomy is a major surgical procedure with inherent risks and the potential for complications. Although hysterectomy yields a high level of satisfaction in that it guarantees the permanent cessation of menstrual bleeding, it is a major procedure. Its invasiveness, morbidity, mortality and costs are well-known disadvantages of the procedure. In addition, hysterectomy can lead to a variety of psychological and physical changes in women. For these various reasons, other, less invasive treatments for DUB have been sought.
Endometrial ablation was adopted in clinical practice toward the end of the 1980s as a less invasive alternative to hysterectomy for treating DUB. Endometrial ablation permits preservation of the uterus and reduces uterine bleeding in most patients. Endometrial ablation is less invasive, more convenient and less expensive than hysterectomy, at least when no complicating gynecologic conditions are involved. Women with dysfunctional uterine bleeding typically prefer endometrial ablation to hysterectomy because the surgery is less invasive, involves less risk of early menopause and sexual impairment, the changes wrought are less profound, and the hospital stay and convalescence are shorter.
First-generation endometrial ablation techniques were primarily based on use of lasers or electrosurgical tools to destroy the entire thickness of the endometrium, thereby avoiding its regeneration. Such techniques are hysteroscopically assisted, with direct, real-time visual monitoring of the uterine cavity. These first-generation endometrial ablation techniques are clearly effective in treating DUB, but have the disadvantage of requiring that they be practiced by skilled operators with specialized training, and may entail surgical complications.
The first-generation techniques are usually performed under general anesthesia but can also be performed with local or regional anesthesia. They require direct visual monitoring of the uterine cavity by means of a hysteroscope and an irrigation fluid. Even if the uterine cavity appears normal on hysteroscopy, an endometrial biopsy is preferably performed because hysteroscopy alone cannot rule out the possibility of a tumor or carcinoma of the endometrium. These techniques are sometimes grouped under the heading of hysteroscopic endometrial ablation techniques. The complications associated with the first-generation ablation techniques include cervical laceration and uterine perforation, injury to the intestine by the conduction of electrical current or direct trauma, fluid overload, allergic reactions and other systemic toxic reactions caused by fluids used to distend the uterine cavity during hysteroscopy, hemorrhage if the ablation extends too deeply into the myometrium and large blood vessels are cut, and (rarely) gas embolism, an unusual but potentially fatal complication of surgical hysteroscopy. Yet these first-generation techniques offer considerable advantages over hysterectomy, in that they take less time to perform and require a much shorter hospital stay and convalescence.
First-generation endometrial ablation techniques include transcervical resection, rollerball ablation, and laser ablation. These techniques are considered to have acceptable risk levels and are currently practiced. However, each requires anesthesia, cervical dilation, and a high level of surgical skill on the part of the medical practitioner. Transcervical resection carries a risk of uterine perforation and of systemic absorption of irrigation fluid as a result of blood vessel exposure, and is contraindicated in cases of hemodynamic instability, coagulopathies, and with patients undergoing anticoagulant therapy. Rollerball ablation carries a somewhat lower risk of uterine perforation and fluid absorption, yet still requires a high level of skill and training. Laser ablation is also causes fewer intraoperative complications than transcervical resection, yet requires even more surgical skill and training, and is a lengthy and costly procedure.
A second generation of endometrial ablation techniques has been more recently developed, in quest of means to destroy the entire thickness of the endometrium while at the same time preventing the associated risks and obviating the skill requirements that the first-generation techniques described above. Most of these newer surgical techniques do not require hysteroscopy and are performed in a ‘blind’ manner.
Manufacturers market most second-generation techniques as procedures that can be performed on an outpatient basis. Indeed, as compared to the first-generation techniques described above, second-generation techniques are relatively faster, easier, are amenable to local anesthesia or narcosis, and cause fewer intra-operative complications. They do, however, carry risk of complications, which include hematometra, infection and internal organ injury.
Given that these new techniques are performed without visual hysteroscopic monitoring (with the exception of hydrothermal endometrial ablation), recommended treatment protocols call for visual examination, pathophysiological study including a hysteroscopy, and an endometrial biopsy prior to treatment. It is also recommended to perform a hysteroscopy after the treatment to check that only the uterine cavity was treated.
Second-generation ablation techniques include thermal balloon ablation, microwave ablation, hydrothermal ablation, impedance-controlled ablation, and cryoablation. While presenting advantages of simplicity when compared to hysterectomy and first-generation ablation techniques, each of these second-generation techniques presents specific limitations and disadvantages.
Thermal balloon ablation is only appropriate for wholly normal uterine cavities. Uterine retroversion and irregularities of the uterine cavity appear to be associated with a greater risk of treatment failure. The treatment is contraindicated in presence of active genital or urinary tract infection and of any anatomic abnormality or any disease that can cause myometrial weakening. In addition, the treatment causes pain due to uterine distention.
Microwave ablation is also appropriate only for the well-formed uterus, because microwave endometrial ablation tends to be incomplete in women whose uterine cavity is hypertrophied or highly deformed. Microwave ablation is also painful, because the cervix must be dilated to 9 mm in order to insert the microwave waveguide, and that dilatation process can be painful even under local anesthesia.
Hydrothermal ablation requires prior diagnostic hysteroscopy to check that there are no uterine perforations and to detect any intrauterine conditions that were not previously diagnosed. It is important to carefully select candidates for this operation, since a large submucosal leiomyoma deforming the uterine cavity will prevent adequate irrigation. Hydrothermal endometrial ablation is contraindicated in presence of active genital or urinary tract infection and of any anatomic abnormality, condition or previous intervention that can cause myometrial weakening, such as a classic cesarean section or a previous transmural myomectomy. Hydrothermal ablation also is painful, in that it requires the cervix be dilated to 8 mm in order to insert the ablation device, and that dilatation process can be painful even under local anesthesia.
Impedance-controlled ablation offers the advantage of not requiring preoperative endometrial thinning. This procedure can be performed at any time during the menstrual cycle, even during menstruation. Impedance-controlled endometrial ablation is contraindicated in the presence of an active genital or urinary tract infection and any anatomic abnormality, any condition or any intervention that can cause myometrial weakening, such as a classic cesarean section or a previous transmural myomectomy. Furthermore, if the uterine cavity is less than 4 cm in length, the treatment will cause burning of the walls of the cervix. It should be noted that the cervix has to be dilated to 8 mm in order to insert the device and that the dilatation process can be painful, even with local anesthesia.
Endometrial cryoablation has typically be performed either by utilizing a single cryoprobe sequentially displaced to and operated at two or more ablation sites during a surgical procedure, or by utilizing up to three independent cryoprobes inserted simultaneously in a uterus, for example, one in the uterine cavity and one in each of the cornua, and using sonography to confirm that the cryosurgical devices are properly positioned in the uterine cavity and to monitor the growth of the ice crystal during the treatment cycles. Cryoablation utilizing these prior art methods has the disadvantage that ablation is not well controlled in that cold is not and cannot be evenly distributed over the endometrial surface, and that the condition of the endometrial surface cannot be observed and evaluated during the cryoablation procedure.
To summarize, it has been seen that some prior art techniques are highly invasive, that other prior art techniques are less highly invasive but are likely to entail surgical complications and require highly skilled operators with specialized training. Therefore there is a widely felt need for, and it would be highly advantageous to have, an apparatus and technique for endometrial ablation which is minimally invasive and does not require highly skilled operators and specialized training.
Further, it has been seen that recently developed endometrial ablation techniques are of limited applicability for use in uterine cavities which are not entirely regular and well formed. The various second-generation techniques tend to be inappropriate for patients having a uterus which is asymmetrical, or which has malformations or large growths, or dissimilar uterine cornuae. Yet, very many patients present a uterine topography which varies from the ideal norm. Thus, there is a widely felt need for, and it would be highly advantageous to have, an apparatus and technique for endometrial ablation operable to treat a wide variety of uterine forms, including asymmetrical forms, those comprising dissimilar uterine cornuae, and those including internal growths and irregularities of the uterine cavity.
It has also been seen that most second-generation endometrial ablation procedures are painful. In particular, most such procedures require anesthesia during performance of the ablative process, and therefore are of limited applicability in simpler clinical settings. Thus, there is a widely felt need for, and it would be highly advantageous to have, an apparatus and technique for endometrial ablation which does not require severe distension of the uterus during treatment, does not require pronounced cervical dilation to permit introduction of an ablative instrument into the uterus. In general, there is a widely felt need for, and it would be highly advantageous to have, an apparatus and technique for endometrial ablation which is not painful, does not require anesthesia during treatment, and which therefore is appropriate for use in an “office visit” setting.
It has further been seen that prior art cryoablation techniques to not provide well controlled and/or uniform application of cold to the entire endometrial surface. Thus, there is a widely felt need for, and it would be highly advantageous to have, an apparatus and technique for endometrial cryoablation able to provide a well-controlled energy transfer uniformly over the entire surface of the endometrium, and which provides means for observing and assessing the condition of the endometrium before, during, and after cryoablation.